Hollow grate-bar



Patented Nov. I, 1898.

No. 6l3,289.

M. MILLER. HOLLOW GBATE BAR. (Application filed Jan. 17, 1898.\

(No Model.)

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UNITED STATES PATENT OFFICE.

MATHIAS A. MILLER, OF AUBURN, INDIANA.

HOLLOW G RATE-BAR.

SPECIFICATION formingpart of Letters Patent No. 613,289, dated November 1, 1898. Application filed January 17, 1898 Serial No. 666 ,910- (No model.)

art to which it appertains to make and use the same, reference being had to the accompanying drawings, which form part of this specification.

My invention relates to improvements inv hollow grate-bars for, steam-boiler furnaces and furnaces of like class. The object of my inventionis toprovide a grate-bar that will economize fuel, consume smoke when coal or wood fuel is used,'and that can be used with natural gas forfuel, or coal or wood at pleasure, simply by means of operating-valves. ,Green sawdust alone can also be used without emitting smoke from the furnaceinto the boiler-room, which is an inconvenience common to furnaces where sawdust is used alone without other fuel. By my invention the heated air which usually escapes with the smoke through the smokestack is also utilized to feed the combustion, thus economizing heat, which is otherwise wasted. 1 attain this object by the device described in the following specification and illustrated by the accompanying drawings, in which' Figure 1 is a perspective view of a steamboiler furnace provided with grate-bars, suction-pipe, and exhaust-blower embodying my improvements, with parts broken away to show construction and arrangement beneath the grates. Fig. 2 is a detail plan View of the blower andfragmentary portions of the suction and blast pipes. Fig. 3 is an end view, in cross-section, of the hollow grate-bar; and Fig. 4 is a detail of a weighted relief-valve.

Similar reference-numerals indicate like parts thoughout the views.

1 is the boiler, 2 the smoke-stack, and 3 a suction-pipe communicating with the smokestack at its upper end and with the exhaustblower at at its lower end. A series of hollow grate-bars 5 5 are longitudinally placed adjacent to each other in position over the ash-pit 8, having their rear ends supported 11 11, by means of which the blast from the blower can be excluded from either pipe or admitted at pleasure.

The grate-bars 5 are hollow and preferably rectangular in transverse section and in two parts 13 and 14, secured together by bolts or in any other suitable manner, or the bar may be integral. In the upper part are a series of perforations, (indicated by dots in Fig. 1,) and in the lower plate 14 are a series of conical-shaped twyers or air-tubes 15, open at each end and registering at their upper ends with the perforations in the upper plate. These tubes for sake of. cheapness in manufacture are preferably cast integral with the plate 14 and fit closely against the under side of the plate 13 andhave small lateral orifices through their walls, (indicated by the numeral 16,) through which communication is made from the interior of the grate-bar to the tubular openings of the pipes.

' At the front part on the under side of the grate-bar is pivotally suspended a horizontal lever 17, having pivotally attached at the front end a relief-valve 18, with an annular flange 20, and at the other end an adjustable counterbalance-weight 19. The stem of the valve 18 is seated in an orifice in the gratebar with the flange 20 against the plate 14, where it is held in its normal position by the weight 19 upon the long arm of the lever. In each pipe 7 is a nipple 10, adapted for attaching a natural-gas-supply pipe for admitting gas into the grate-bar, and beneath each nipple is a stop-cock 23 for excluding the gas from the pipe 7 below the said nipple.

In the suction-pipe 3 is a damper 21 and a from the suction-pipe 3 and forced through the pipe 6 and the branch pipe 9 and the apertures 12 into the space beneath the gratebars and through the air-tubes 15 into the fuel placed on the grate-bars. The air-blast will also pass through the air-pipes 7 into the grate-bars and through the orifices 16 into the tubes 15 and thence into the fuel in like manner. hen gas is used for fuel, the stopcocks 23 are closed, thus excluding the air from the pipe 6, and the gas, passing into the grate-bar, escapes through the orifices 16 into the tubes 15, where it mixes with the air-blast from the pipe 9 in proper proportions to form the desired fuel.

By means of the gates 11 11 the air can be forced through either the pipes 7 or the branch pipe 9 independently of each other or through both simultaneously, as may be desired. It is obvious that the air can be excluded from the interior of the grate-bars by means of the gate 11 or by the stop-cocks 23; but it is more convenient to use the gate for regulating the supply when gas is not used, and when gas is used it is safer to exclude its admission into the pipes below the stop-cocks by using them than to rely upon the gate, as the gas in the latter case would flow into the pipe 6 up to the gate, and thus become a dangerous element.

The suction-pipe 3 when the blower is in operation will draw the heated air and smoke from the smoke-stack and which will be forced into the pipe 6 to feed the flame in the fuel in a manner which will be readily understood without a detailed explanation.

It will be seen that the smoke will not en ter the boiler-room, as the blast will force it directly to the fuel and become a part of the same. By closing the damper 21 and opening the register 22 cold air is admitted to the blower.

The valve 18 is for the purpose of an exit for any foreign matter that may enter the grate-bar, which can be forced out by the airblast when the valve is open. It also acts as a relief when the air-pressure is too strong in the grate-bar. Of course when gas is used for fuel the valve must be securely closed by a proper adjustment of the weight 17 to prevent its escape into the ash-pit. The gratebars can be supplied with air through the blast-pipe from the blower without the supply from the smoke-stack but by combining the heated air and the smoke a great saving of fuel is effected. A furnace thus equipped will readily burn pure green sawdust, coal, wood, or gas, and, indeed, any kind of fuel but oil; but it can be adapted to use oil also.

By the construction described a change can be quickly made from natural gas to coal or wood, or vice versa, by simply operating a few valves, a feature which will be appreciated by those using natural gas, the flow of which is sometimes obstructed.

\Vhile the tubes 15 are shown as cylindrical and preferably conical, it is obvious that they may be polygonal and also of uniform size throughout their length.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. A hollow grate-bar having interior vertical air tubes or pipes in close contact with the inner upper and lower surface of the bar and provided with exterior openings at each end and orifices in the walls of the pipes for communication between the interior of the grate-bar and the pi pe-openin gs, and an opening upon the under side of the grate-bar adapted to be connected with a pipe or duct whereby a blast of air or gas may be forced through the grate-bar and the vertical pipes into the fuel placed upon the grate-bar.

2. A hollow grate-bar having interior vertical air tubes or pipes in close contact with the inner upper and lower surface of the bar and provided with exterior openings at each end and orifices in the walls of the pipes for communication between the interior of the grate-bar and pipe-openings, and an opening upon the under side of the grate-bar adapted to be connected with a pipe or duct whereby a blast of air or gas may be forced through the grate-bar and-the orifices in the vertical pipes into the fuel placed upon the grate-bar in combination with a valve 18 pivotally seated in an aperture in the under side of said gratebar and attached to a pivoted lever with counterbalance adjustable weight all substantially arranged as described and shown.

3. A two-part hollow grate-bar whose detachable base is provided with a series of upright projections having central openings for the natural draft adapted to register with the draft-openings in the top of said bar, the said projections having suitable lateral openings to admit the blast from the interior of the bar and in close contact with the inner surface of the upper part of the bar, and an opening in the said grate-bar adapted for connection with a suitable blast-pipe all arranged as described and shown.

4. A series of two-part hollow grate-bars for a furnace of the class described, each bar hav ing a detachable base with a series of vertical integral tubular projections for the natural draft and adapted to register with draft-openings in the top of said bar, the said projec tions having suitable lateral openings to admit the blast from the interior of the bar; an opening in said bar adapted to be connected with a pipe or duct the said pipe or duct connected at one end with the grate-bar and at the other with a blast-pipe and blower and provided with a nipple and stop-cock for the purpose stated; the blast-pipe and blower; a suction-pipe communicating with the smokestack of the furnace and the said blower whereby heated air may be drawn from the smoke-stack and forced by the blower into the grate-bar and through the said lateral Openings into and through the fuel placed upon said grates all arranged substantially as described and shown.

5. A series of two-part hollow grate-bars for a furnace of the class described, each bar having a detachable base with a series of vertical integral tubular projections for the natural draft and adapted to register with draft-openings in the top of said bar, the said projections having suitable lateral openings to admit the blast from the interior of the bar; a pipe or duct connected at one end with the said bar and at the other end with a blast-pipe 6; the blast-pipe having a branch pipe 9 and each provided with a gate or cut-0E as stated; the blower 4, a suction-pipe communicating with the smoke-stack of the furnace and the said blower whereby heated air may be drawn from the smoke-stack and forced by the blower into the pipe 6 and means for excluding the air-blast from either pipe 6 or the branch pipe 9 and means for regulating and relieving the pressure of the forced blast in the said gratebars all arranged substantially as described and shown.

6. A series of two-part hollow grate-bars for a furnace of the class described, each bar having a detachable base with a series of vertical tubular projections for the natural draft and adapted to register with draft-openings at the top of the bar the said projections having suitable lateral openings to admit the blast from the interior of the bar; a pipe or duct con nected at one end with said bar and at the other with a blast-pipe 6 and provided with a nipple and stop-cock for the purpose stated; the blast-pipe 6 having the blast branch pipe 9 and each provided with a gate as stated; a blower; a suction-pipe 3 communicating with the smoke-stack and the blower; a valve 18 pivotally suspended upon the lever 17 hav= ing the adjustable weight 19 and all arranged substantially as described and shown and for the purpose stated.

Signed by me, at Auburn, Indiana, this 14th day of January, 1898.

MATHIAS A. MILLER; Witnesses:

ISAAC HAGUE, JAMES E. RosE. 

